Question: $ B = \left[\begin{array}{rrr}0 & 2 & 1 \\ 2 & 0 & 0 \\ 2 & 2 & 0\end{array}\right]$ What is $ B^{-1}$ ?
$ = \left[\begin{array}{rrr}0 & \frac{1}{2} & 0 \\ 0 & -\frac{1}{2} & \frac{1}{2} \\ 1 & 1 & -1\end{array}\right]$